This invention relates to processes, including continuous processes, for the production of silylated derivative compounds of organic halides and alkenes, including organochlorosilanes and dipodal silanes, useful in a variety of applications including as coupling agents and as surface modifiers of substrates related particularly to water repellency and diagnostic applications.
It has been reported in U.S. Pat. No. 6,392,077 of Jung, et al. that organochlorosilanes can be prepared in a batch process by a dehydrohalogenative coupling reaction of an alkyl halide with a hydrido functional chlorosilane in the presence of a solid phosphonium catalyst or solid supported catalyst, as further described in U.S. Pat. No. 4,613,491 of Jung, et al.
In a similar manner, dipodal silanes are produced either in a two step process in which the dehydrohalogenative coupling reaction of an alkene with a chlorosilane occurs, first immediately followed by a hydrosilylation reaction or in two hydrosilylation steps. However, this reaction also requires the use of a solid catalyst or solid supported catalyst. This process also requires charging a solid catalyst to a batch reactor and, once the reaction is complete, removing the catalyst from the reaction mixture either by filtration or distillation. On a commercial scale, this is a labor- and time-consuming operation.
The reactions reported by Jung are carried out in sealed tube reactors at estimated pressures that exceed 1000 p.s.i. The use of sealed tube reactors also causes redistribution of initial by-products of the reaction resulting in such hazardous materials as dichlorosilane and silane.
Prior to the present invention, the reaction of alkyl halides and hydridochlorosilanes was commercially carried out by a batch process, which included a dehydrochlorinative coupling reaction in the presence of an amine base acceptor and sometimes a copper catalyst (Benkesser et al, J. Am. Chem. Soc., 91 (13):3666–67 (1969); Furuya et al, J. Organomet. Chem., 96: C1–C3 (1975); Corriu et al., J. Organometal. Chem., 562:79–88 (1998)). This is a cumbersome process which requires reacting a chlorosilane with a stoichiometric amount of an amine, which generates a considerable amount of waste by-products. This process also generates amine hydrochloride salts which must be removed by filtration. Amine hydrochloride salts are difficult to filter and are often soluble in the product. As a result, further filtration after product purification is required, and still the amine hydrochloride salts continue to drop out of solution after the products have been standing for extended periods of time.
Thus, the large scale production of organochlorosilanes and dipodal silanes by the above mentioned batch process is cumbersome, expensive and, in the case of the Benkesser process, generates excessive waste, such as amine hydrochloride salts and, in the Jung process, is subject to significant by-product generation, attributed to prolonged exposure to the catalyst at elevated temperatures and pressures resulting in the formation of by-products, such as dichlorosilane and silane gas which are difficult to handle and pyrophoric.